1. Field of the Invention
The present invention relates to medical/surgical devices and apparatus and methods of using them, and more particularly, to such apparatus and devices incorporating magnets.
2. Description of Related Art
Trocars are commonly used to provide access to internal body parts during surgery. In its most basic form, a conventional surgical trocar includes a base having a depending elongated cannula, with a lumen extending axially of the cannula and through the base. In use, the cannula extends into a body cavity of the patient to enable a surgical procedure to be performed without a large incision or major invasion of the interior of the patient's body. The trocar base remains outside the patient. The surgeon passes through the trocar lumen a surgical instrument, such as endoscope or any other device typically used in this type of minimally invasive surgery, to position it within the patient's body at the desired location. Examples of this type of trocar assembly are shown in U.S. Pat. No. 4,535,773, U.S. Pat. No. 5,338,307, U.S. Pat. No. 5,397,314, U.S. Pat. No. 5,882,344, U.S. Pat. No. 5,423,761, German Patent Publ. No. 28 00 607, French Patent No. 2,719,210, Japanese Patent Abstract No. 2000/000246, and International Appln. No. WO01/43812.
This type of minimally invasive surgical procedure may require that the anatomical region or body cavity implicated in the procedure be insufflated with a gas, such as carbon dioxide, or in some cases a liquid, such as a saline solution. Insufflation distends the region or cavity in order to provide the surgeon with sufficient space to carry out procedures such as laparoscopy, arthroscopy, hysteroscopy and hydro-laparascopy. Conventionally, the patient is insufflated through the trocar or through a Veress needle before the procedure is begun. It is preferable that adequate insufflation be maintained, to ensure that the surgeon's vision of the target area remains unimpaired throughout the procedure and to prevent the necessity of interrupting the procedure to reinsufflate the patient. For that reason, a trocar will typically include some sort of valve to prevent the escape of the insufflating gas. However, the construction of known valves normally prevents them from sealing perfectly around a surgical instrument shaft, which can result in the escape of insulating gas from the patient. Examples of trocar lumen valves and seals are shown in the above-mentioned U.S. Pat. No. 4,535,773, U.S. Pat. No. 5,397,314, U.S. Pat. No. 5,423,761, German Patent Publ. No. 28 00 607, French Patent No. 2,719,210, Japanese Patent Abstract No. 2000/000246, and International Appln. No. WO01/43812, and also in U.S. Pat. No. 5,916,198.
In constructions where the trocar valve or seal may permit insufflation gas to escape around the instrument shaft, insufflation pressure can be maintained when the surgical instrument is in place by using a reducer cap at the proximal end of the trocar base. U.S. Pat. No. 5,338,307 describes a reducer cap that is capable of movement into position to present to the surgical instrument an opening that fits closely to the instrument shaft. While the cap in this patent serves its intended purpose, it is cumbersome to manipulate into and out of position. The kinds of minimally invasive procedures with which these trocars are used are typically performed in darkened operating rooms, so that the surgeon can see more clearly a video feed from the surgical site within the patient's body. However, in a darkened room it is more difficult to perform the manual manipulation required to put the reducer cap described in U.S. Pat. No. 5,338,307 onto the trocar in the first place, and to remove it from the trocar if that becomes necessary and then replace it again if need be.
Conventional reducer caps may require the surgeon or an assistant to use two hands to place the cap and correctly orient it for attachment to the trocar. This complicates the situation when the surgeon needs to introduce a curved needle and suture, or remove tissue, through the trocar, because these maneuvers may require that the trocar cap be removed and then subsequently replaced. If replacement of the cap requires the surgeon and/or the assistant to release their hold on the surgical instruments and look away from the video monitor displaying the operative site within the patient to manipulate the trocar cap, it interrupts the procedure. If the procedure is being performed in a low-light environment, using these known reducer caps is even more disruptive because it will be difficult to see the cap and trocar clearly after looking at a relatively bright video monitor. To compensate for this, low intensity illumination can be projected at the trocar, but that in turn can detract from the clarity and sharpness perceived on the video monitor. It would therefore be advantageous to have a cap that can be easily and quickly removed and replaced on the trocar without requiring precise manipulation by the surgical team so that cap removal/replacement does not disrupt ongoing surgical procedures.
At the same time, there is a need to provide the trocar with sufficient lateral stability when in place in a patient. If the trocar base extends too far outside the patient, the resulting high profile can make it difficult to maintain the seal between the patient's skin and the trocar cannula. Incorporating prior art lumen seals into the trocar base tends to increase the length of the base, thus resulting in a higher profile trocar when in use. Another important consequence of this instability is that it can make it very difficult for the surgeon to introduce the instrument through the lumen of the trocar cap. As discussed above, a purpose of the cap is to present to the surgical instrument a lumen that fits snugly around the instrument shaft. If the trocar is prone to movement, it makes it even more difficult to align the instrument shaft with the tightly fitting cap lumen.
Another stability problem presents itself when a trocar of a given length cannot be inserted into the patient far enough so that the underside of the trocar base rests snugly against the patient's skin. U.S. Pat. No. 5,882,344 explains that this can happen if the trocar cannula is sufficiently long to penetrate the patient's internal organs. Partial insertion of the trocar will solve the problem, but at the expense of preventing the trocar base from bearing on the patient's skin, thus sacrificing trocar stability. U.S. Pat. No. 5,882,344 provides an adjustable length cannula to address this problem, but the decreased stability from incorporating a lumen valve into the trocar remains.
Another aspect of minimally invasive surgical procedures is that it is sometimes necessary to align surgical instruments across an internal tissue boundary. For example, it is often necessary to pass a suturing needle through an internal tissue boundary at a precise location. There are numerous devices and techniques employing magnetism to align, manipulate, or effect placement of surgical and medical devices. Examples are shown in U.S. Pat. Nos. 3,961,632, 4,809,713, 5,417,701, 5,824,009, 6,068,637, 6,159,224, 6,450,950, 6,522,909, 6,524,303, 6,352,543, 6,652,540, and 6,655,386. However, none of those devices or the manner of using them appears to be readily adaptable to providing alignment of a surgical device such as a suturing needle blindly across an internal tissue boundary.
A related problem is encountered with a vascular access port (“VAP”) implanted in a patient to enable repeated administration of medications without requiring a vein, artery, or other anatomical structure to be punctured each time. The implanted VAP is connected permanently to a vascular structure or other anatomical region and the medication is introduced into the VAP with a hypodermic needle. Typical VAPs have a membrane or septum, and a hypodermic needle is used to puncture the patient's skin and introduce the medication through the septum into a plenum in the VAP. For proper administration of the medication, the hypodermic needle must be lined up with the septum before the needle is passed through the patient. U.S. Pat. No. 5,758,667 discloses a magnetic device for locating the septum of an implanted medication dispenser. While this device should be able to locate the septum under optimum conditions, it is constructed in a way that makes it somewhat cumbersome to introduce the medication once the implanted septum is located. It is also susceptible to misalignment of the hypodermic needle and the septum if the relative position of the VAP device shifts under the patient's skin.
Another medical procedure that is often performed is the implantation of a plug into an internal ostium of a subject, such as a tubal sterilization procedure using ostium plugs in the openings of the subject's Fallopian tubes. These plugs typically include barbs that engage the internal walls of the tubal ostia, causing minor trauma. This trauma, along with local tissue reaction to biomaterials within the construction of the plug, create scar tissue that firmly holds the plug in place. U.S. Pat. Nos. 6,357,443 and 6,712,810 discuss examples of such plugs. Such tubal sterilization procedures are not easily reversible. For example, to reverse a sterilization effected by the technique discussed in U.S. Pat. No. 6,357,443, the entire plug must be removed. Tubal sterilizations of this type would be more attractive to patients if there were a more reliable and simpler technique for reversing the sterilization.